The present invention relates to a food processing plant, of the type including a food processing apparatus provided with means for setting set-point parameters for the operation of this apparatus and with means for controlling the operation of the apparatus on the basis of these set-point parameters.
The food processing apparatuses used in such plants are, for example, refrigerating apparatuses such as cryogenic deep-freezing tunnels or surface-crusting tunnels. These plants may also employ cooking ovens or apparatuses for dispensing precise quantities (drops) of liquid nitrogen into flexible plastic bottles before sealing, or into aluminium cans.
An example of a cryogenic tunnel for the processing of food is described in Spanish Patent Application P9500983 filed on May 23, 1995 in the name of SOCIEDAD ESPANOLA DEL OXIGENO, S.A.
The means for controlling the operation of such apparatuses on the basis of the predetermined set-point parameters may be of varying degrees of sophistication. In particular, these apparatuses may include one or more control loops acting on at least one of the set-point parameters.
Under these conditions, the complexity of the food processing apparatuses may lead to them operating imperfectly. In particular, modifications in the normal conditions in which the apparatuses are used, for example by a variation in the loading factor of the latter or a variation in the external temperature, may cause poor operation, in particular by a drift in the settings.
Thus, it is found in practice that such plants employing sophisticated actuation and control means exhibit significant risks of malfunction and of instability, which may finally lead to the fact that the observed performance is inferior to that of apparatuses of simpler design.
Over a more or less period of use, the operator of such an apparatus draws no benefit from the high theoretical performance of the apparatus that he has acquired, because of the many periods of malfunction of the latter.
Of course, these malfunctions have economic implications related, in particular, to instabilities in the quality of the products obtained, or to the erratic consumption of certain consumables, such as the liquid nitrogen used to refrigerate the food.
In this particular field of food processing, malfunctions of a processing apparatus have, in point of fact, serious consequences with regard to the quality of the processed products. Thus, when the apparatus is functioning unsatisfactorily, the processed products run the risk of being unfit for consumption and must be destroyed, thereby seriously affecting the overall productivity of the plant.
In conclusion, the food processing apparatuses, although theoretically of high performance in the absence of any disturbance, do not meet the requirements of users because of significant vagaries in their operation.
It should be noted that the owner of such plants, faced with these problems, is usually at a loss since he has only very rarely the ability to understand the phenomena involved and to bring them under control, and still less any proposals for immediately solving these problems, while potentially large quantities of products are held up, waiting until they can be processed satisfactorily.
In addition, not only does he not usually have the skill to diagnose the malfunctions of one of his apparatuses, but he may also be faced with having to tackle the problem of simultaneous malfunctions of several apparatuses (of the same or different type) on his site.
Investigations undertaken by the Applicant on this subject allow him to provide here a few illustrations of such malfunctions/drifts and of the way in which they may severely compromise the productivity of the plant.
Let us take, for example, the case of a cryogenic tunnel with control of the temperature in the tunnel, using a measurement of the temperature inside the chamber and, optionally, a feedback action, depending on the result of a comparison between the measurement and a temperature set-point value, on the setting of a cryogenic-liquid feed valve of the tunnel.
In practice, temperature drifts are observed, for example during sudden variations in the loading factor of the tunnel or in the surrounding environmental conditions. These drifts may sometimes be linked to a malfunction of the cryogenic-liquid feed valve whose curve of opening/closing over time is unable to cope with the speed which would be necessary to maintain the required temperature in the tunnel (for example, very closely separated times for opening and closing the valve, which would seriously jeopardize its future reliability).
To limit oneself in such a case to a simple measurement of the temperature would not therefore be completely representative of the actual operation of the apparatus. As developed further in the context of the present application, it is advantageous to acquire additional information which is representative of the actual operation of the apparatus, so as actually to be in a position to detect and understand possible malfunctions of and drifts in the apparatus.
The object of the present invention is to provide a solution to the problems mentioned hereinabove and, in particular, to propose a food processing plant employing a processing apparatus which is reliable and can ensure high productivity without any risk in respect of product quality.
For this purpose, the subject of the invention is a food processing plant of the aforementioned type, characterized in that it includes:
means for acquiring information relating to the actual operation of the apparatus; PA1 a unit for monitoring the apparatus, this being located remote from the latter and designed to detect anomalies in the operation of the apparatus; and PA1 means for communicating the said information relating to the actual operation of the apparatus from the said apparatus to the said remote monitoring unit. PA1 the said means for communicating the said information include means for processing the said information in order to generate a message representative of the actual operation of the apparatus, and means for sending the said message to the remote monitoring unit, which unit includes means for receiving the said message and means for processing the said message for the purpose of detecting operating anomalies; PA1 the said means for controlling the apparatus include a control loop acting on at least one of the set-point parameters; PA1 the said control loop includes a controller associated with modifiable control parameters, the remote monitoring unit including means for generating modified control parameters, for the said controller and means for sending the said modified control parameters to the said communication means, which communication means include means for receiving the said modified control parameters sent by the said remote monitoring unit, and the said control loop includes means for modifying the control parameters on the basis of the said modified control parameters received by the said communication means from the said remote monitoring unit; PA1 it includes means for acquiring the set-point parameters that have been set, which means for acquiring the set-point parameters are linked to the said means of communication from the said apparatus to the said remote monitoring unit for the purpose of transmitting the said acquired set-point parameters to the said remote monitoring unit; PA1 the remote monitoring unit includes means for generating modified set-point parameters and means for sending the said modified set-point parameters to the said communication means, which communication means include means for receiving the said modified set-point parameters sent by the said remote monitoring unit, and the said means for setting the set-point parameters include means for modifying the set-point parameters on the basis of the said modified set-point parameters received by the said communication means from the said remote monitoring unit; PA1 the said apparatus is a deep-freezing tunnel of the cryogenic type and the said information acquiring means include means for acquiring at least one of the following items of information: the temperature in the chamber of the tunnel, the quantity of cryogenic fluid consumed, the rate of outflow of vaporized cryogenic fluid and the state of operation of at least one functional device of the tunnel, in particular a valve; PA1 the tunnel includes a conveyor for transporting the food to be processed and the said information acquiring means include a sensor for detecting movement of the conveyor; and PA1 the said apparatus is an apparatus for dispensing precise quantities of a cryogenic liquid, in particular liquid nitrogen, and the said information acquiring means include means for detecting the state of operation of at least one functional device of the apparatus, in particular a valve.
Depending on the particular embodiment, the plant may include one or more of the following characteristics: